Through the same chain it is narrated: A man came and greeted the Messenger of Allah (peace and blessings be upon him) with salam: 'As-salamu alaykum, O Messenger of Allah!' (Peace be upon you). He (peace and blessings be upon him) said: "'Wa alayka as-salamu wa rahmatullah' (And upon you be peace and the mercy of Allah)." Then another man came and said: 'As-salamu alayka, O Messenger of Allah, wa rahmatullah!' (Peace be upon you and the mercy of Allah). He (peace and blessings be upon him) said: "'Wa alayka as-salamu wa rahmatullahi wa barakatuh' (And upon you be peace, the mercy of Allah and His blessings)." Then another man came and said: 'As-salamu alayka, O Messenger of Allah, wa rahmatullahi wa barakatuh!' (Peace be upon you, the mercy of Allah and His blessings). The Messenger of Allah (peace and blessings be upon him) said to him: "'Wa alayk' (And upon you)." The man said: O Messenger of Allah! So-and-so and so-and-so came to you, and you answered them better than you answered me? The Messenger of Allah (peace and blessings be upon him) said: "You left nothing remaining in the greeting. Allah, the Mighty and Majestic, says: 'And when you are greeted with a greeting, respond with one better than it or return it' [Surah al-Nisa: 86], so I returned the same greeting to you."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6089